Does anyone know how to? I have one of Jim Harding's book, Amphibians and Reptiles of the Great Lakes Region, and it gives a difference. But I asked him (we exchange email) and he said the difference in webbing of the hind feet (in the book) really is too small to tell.-----Least favorite quotation: "These foul and loathesome animals are abhorrant because of their cold body, pale color, cartilaginous skeleton, filthy skin, fierce aspect, calculating eye, offensive smell, harsh voice, squalid habitation, and terrible venom; and so their Creator has not exerted his powers to make many of them." - Carolus Linnaeus